Combustion apparatus



2 Sheets-SheekI l H. A. DREFFEIN COMBUSTION APPARATUS Filed March 22', 1939 Herz Sept. 9, 1941.

Sept. 9, 1941. H. A. DREFFEIN COMBUSTION APPARATUS Filed March 22, 1959 2 Sheets-Sheet 2 lPatented Sept. 9, 1941 UNITED STATES PATENT oFEicE 2.255.540 oonnus'noN Arrmws um; .4. onrein, emma, n1. Application March 22, 1939, Serial No. 283,447

(ci. 12s-a1) A Claims.

My invention relates generally to combustion apparatus, and more particularly to such apparatus which is adapted to be utilized as a heater for heat treating furnaces, and the like.

Because of the expense of operating electrical heating apparatus in heat treating furnaces where control of the atmosphere surrounding the treated work-pieces is desirable, some fuel burn-- ing heaters have been proposed. In such fuel burning heaters, it is necessary to completely enclose the ame with respect to the heat treating portion of the furnace, so that oxidation and scaling of the treated work-pieces in the exhaust fumes of the flame are prevented. 'I'he enclosure of the ame gives rise to problems including the effecting of practically complete combustion of the fuel and also control of the heat distribution along and around the heater. These and other considerations have been taken into account in the development of the combustion apparatus which comprises the subject matter of my present invention.

It is an object of my invention to provide a fuel burning heater for heat treating furnaces, and the like, the installation of each of which requires only a single opening inrone side of a furnace.

Another object of my invention is to provide a fuel burning heater for heat treating furnaces, and the like, which has an enclosure segregating the flame and products of combustion from the interior of the furnace and which is designed to give practically complete combustion of the fuel as Well as desirable heat distribution and radiation.

E Another object of my invention is to provide a fuel burning heater having an enclosed burner which is constructed and arranged to control the mixture of fuel and air in such a way that combustion is distributed within the confines of the enclosure. f

Another object of my invention is to provide a fuel burning heater in which the mixture of fuel and air is distributed and combustion is improved by eifecting agitation and mixture of the air and fuel.

Another object of my invention is to provide an efiicient fuel burning heater, fuel and air both being fed into the burner. at the same end thereof at which the products of combustion are exhausted and in which the heat from the exhaust heats the air entering the heater.

Another object of my invention is to provide an enclosed fuel burning heater that can be economically manufactured and installed for use.

Other objects and advantages of the invention will be apparent as it is better understood from the following description which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

In the drawings:

F18. 1 'is a side elevation of a preferred embodiment of my invention with a part thereof shown in section;

Fig. 2 is an enlarged fragmentary view of a part of the structure shown in Fig. 1;

Fig. 3 is a sectional view taken substantially on line 3-3 of Fig. 2 and in the direction of the arrows:

Fig. 4 is a sectional view taken substantially on line 4-4 of Fig. 1 and in the direction of the arrows;

Fig. 5 is a fragmentary view of a modified form of my invention;

Fig. 6 is a side elevation of a modified form of my invention with parts thereof shown in section;

Fig. 7 is an enlarged fragmentary sectional vlewof a portion of the :structure shown in Fig'. i

Fig. 8 is a sectional view taken substantially on the line 8 8 in Fig. 7 and tion of the arrows; and

Figs. 9, 10 and 11 are respectively sectional views taken substantially on lines 9 9, I0-I0 and H-H of Fig. 6 and looking in the direction of the arrows.

Having particular reference to the drawings, walls of a furnace such as those utilized for heat treating, and the like, are indicated at 20 and 2l. These walls 20 and 2| are of the usual construction and are made up of heat insulating material andl lined with a heat-resistive material such as fire brick. The wall 20 has an opening 22 therein through which an elongated and preferably tubular burner housing 23 extends into the furnace. The lburner housing 23 has an open end at 24 outside of the furnace and a closed end 25 inside the furnace. In a preferred construction, a lug 26 on the closed end 25 of the housing rests against a support 2l that is secured to the wall 2| of the furnace. An air feed pipe 29 is mounted within and spaced from the housing 23 and is preferably substantially concentric with respect to the housing. 'I'he air feed pipe 29 has an open end 30 sumciently spaced from the closed end 25 of the housing to provide a combustion chamber or space at 3l within the closed end of the housing. The air feed pipe 29 also has longitudinally spaced groups of openings 33, 34 and 35 therein which are all within and covered by the housing 23. The individual openings of the groups are preferably circumferentially spaced around the air feed pipe. Outwardly flaring walls 36, 31 and 38 that are preferably arcuately shaped are secured to the outer surface of the air feed pipe adjacent the groups of openings 33, 34 and 35,

looking in the direcand preferably cover those openings to change the direction of flow' of air from within the air feed pipe that passes through the openings 33, 34 and 35. The outwardly flaring walls 34, 31 and 38 each include a flat portion angularly disposed with respect to the air feed pipe 23 through which a series of openings such as 33, 40 and 4| are drilled at an angle with respect to the axis of the air feed pipe so that circumferential and axial movement are imparted to the air discharged therethrough into the housing 23. The circumferential and axial movements of `the air effect a better mixture of air and fuel as will be more fully described. Feet such as 42 are secured to the outer surface of the outwardly aring walls 36, 31 and 38 to support the air feed pipe within the housing 23 and to maintain spaced relation between the housing and the air feed pipe, so that space is provided for combustion around the outer surface of the air feed pipe and within the housing. The feet 42 are preferably angularly disposed, so as to tend to maintain, rather than to interfere with the circumferential or rotarymovement of the air.

An open end 44 of the air feed pipe opposite the end 30 communicates with a baffled preheater 45 and through that preheater communicates with an air supply main 46 which comprises suitable pipe connections and a shut-off valve 41. The baffled preheater 45 comprises longitudinally extending baflies 48 and a separating ring 49. The baffles 48 and separating ring 49 provide channels 50 for the passage of air and channels for the passage of exhaust gases and products of combustion. The ring 49 separates the air channels 50 from the exhaust channels 5| and the preheater 45 fits into the housing 23, so that the air passing into the air feed pipe 29 through the preheater 45 is heated by the heat transferred through the preheater from the exhaust gases. An exhaust pipe 52 is secured to the open end of the housing 23 by a suitable coupling 53 and communicates with the interior of the housing through the exhaust channels 5|. The coupling 53 is provided with a plug 54 through which the air supply main passes for connection with the preheater 45.

A fuel feed pipe 55 extends through the preheater 45 and air feed pipe 29 to a point near the open end 30 of the air feed pipe. The fuel feed pipe 55 is connected to a fuel supply main 56 comprising suitable pipe connections and a shut-off valve 51. The outer diameter of the fuel feed pipe is smaller than the inside diameter of th air feed pipe, so that the air fed through the air feed pipe is fed therethrough around the outside of the fuel feed pipe. Spaced relation is maintained between the fuel feed pipe and the air feed pipe by feet-such as 59.

Fuel such as gas is fed from the fuel supply main 56 through the fuel feed pipe 55 and discharged from the open end of the fuel feed pipe into the space or chamber 3| and toward the closed end 25 of the housing 23. In the preferred embodiment of my invention, the open end 30 of the air feed pipe is sufficiently restricted that only from 30% to 50% of the air required for complete combustion of the fuel is dischargedv at the open end 30 of the air feed pipe. In determining the percentage of air that is mixed with the fuel in the space or chamber 3| at the closed end of the housing, it is particularly desirable to keep the percentage of air sufficiently high to prevent cracking of the fuel and consequent deposits of soot or carbon in the space 3|.

assegno It has also been found that the particular percentage depends somewhat upon the heating of the air that is mixed with the fuel since by heating the air, the percentage that need be mixed with the fuel to prevent cracking and soot formation may be considerably reduced. The percentage of air that is mixed with the fuel in the space or chamber 3| is also somewhat dependent upon the heat distribution that is desired along the surface of the housing 23 and upon the size and distribution of the openings 33, 34 and 35 as well as the openings 39, 40 and 4I. It is natural that for best efficiency, sufficient air should be discharged through the various openings in the air feed pipe 29 to effect practically complete combustion of the fuel within the housing 23. However, the distribution of the combustion and the heat therefrom along the surface of the housing 23 is not only controlled by the longitudinal displacement of the openings 33, 34 and 35, but is also partially controlled by the sizes of the openings 33, 34 and 35 and the openings 39, 40 and 4|. That is, the openings 33, 34, 35, 39, 40 and 4| meter the air discharged therethrough and thus control the distribution of combustion along the inner surface of the housing 23.

From these considerations, it will be understood that the sizes and number of the openings associated with each of the outwardly flaring walls 36, 31 and 33 need not be the same, but are preferably preselected to effect the desired distribution of heat. As an additional consideration with respect to the efficiency of combustion, it is desirable and preferable that the air and fuel are thoroughly mixed. To effect such mixture, it is a feature of the structure disclosed herein that the air is projected axially by the openings 39, 40 and 4| through which the air is discharged and that the openings are preferably angularly disposed to effect rotary or circumferential movement of the air. By projecting the air into the combustion chamber at the desired angle and Velocity, movement or agitation for proper mixture of fuel and air is produced and maintained. This movement prevents separation of the fuel and air due to their normal difference in density.

Referring particularly to Fig. 5, it is sometimes preferable to increase the radiating surface and the diameter of the housing. This is particularly true in the case of longer housings and where it is desired that the flame penetrate farther from the end of the air feed pipe 29. Longer housings require more fuel for heating and also make increased space and radiating surface desirable at the closed end of the housing to prevent overheating of the housing walls. In such instances, the side wall of the housing 23 is preferably expanded as at 60 to provide increased housing surface at the end. This feature not only aids in securing improved combustion at the ends of long housings, but also affects the heat distribution by increasing the radiating surface at the closed end of the housing. The length of the burners is, of course, determined by the width of the furnace in which the burners are to be used and the distribution of heat within the burners, as well as the radiation therefrom. Another factor of determination is the distribution desired from a particular use of the furnace. By increasing the diameter of the closed end of the housing, the flame carries to, or farther toward the closed end to effect better heat distribution in a long housing.

Having particular reference to Figs. 6 to 11, inclusive, like parts bear reference numerals similar to those previously used. In the modivided for manually regulating or controlling the discharge of air through the openings 33, 34 and 35 in the air feed' pipe 23. The fuel pipe 55 is -rotatably mounted in the air feed pipe 29 and has an operating handle 10 secured to the outer end thereof for manually rotating the fuel pipe 55 with respect to the air feed pipe 23 and housing 23. By the provision of a flexible union 1l through which the fuel pipe 55 is connected to the fuel supply main 55, the rotation of the fuel feed pipe may be effected without changing the flow of fuel therethrough. A series of vanes or flanged rings 12, 13 and 14 are secured to the fuel feed pipe 55 in substantial alignment with each of the groups of openings 33, 34 and 35. The vanes or flanged rings are preferably held in position by welding, as at 15. The vanes or flanged rings 12, 13 and 14 have openings 16, 11 and 18, respectively, correspond to the openings 33, 34 and 35, respectively, in the air feed pipe 29, and as shown in Figs. 9, 10 and 11. The openings 16, 11 and 18 are preferably somewhat larger than the openings 33, 34 and 35 or are circumferentially elongated so as to permit some rotary movement of the vanes without restricting the passage of air through the openings 33, 34 and 35. In some instances, it is also preferable to stagger or circumferentially -displace the openings 16, 11 and 18 in the vanes or flanged rings 12, 13 and 1l!` respectively, in order that the restriction of the air flow through the openingsv 33, 34 and 35 is varied by different amounts. By thus staggering the openings, the distribution of the heat in the burner is controlled along with the total heat output thereof. Except for the feature of controlling the air discharged through the openings 33, 34 and 35, the operation of the burner shown in Figs. 6 to 11, inclusive, is similar to that previously described with respect to the burner shown in Figs. l to 5, inclusive.

It is thought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will be apparent that various changes may be made in the form, construction, and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

What I claim as new and desire to cover by Letters Patent is l. Combustion apparatus comprising, in combination, a fuel feed pipe open at one end and adapted to be connected to a gas supply main at the other end, `an air feed pipe having an inside diameter greater than the outside diameter of the fuel feed pipe, said air feed pipe surrounding the fuel feed pipe to provide an air passage around the outside of the fuel feed pipe and being open at one end adjacent the open end of the fuel feed pipe, the open end of the air feed pipe being restricted a predetermined amount, said air feed pipe having longitudinally spaced groups of circumferentially spaced openings intermediate the ends thereof, covers having an outwardly projecting wall secured to the air feed pipe adjacent each of said groups of openings,

said covers having openings therein angularly disposed to effect circumferential and axial movement of air discharged therethrough, a housing coveringthe open ends of the fuel and air feed pipes and the covers, an exhaust pipe flcation disclosed in `these figures, means is proi communicating with the housing, and means within the housing for increasing the heat transfer from the exhaust gases to the air injected through the air feed pipe.

v2. Combustion apparatus comprising, in combination, a fuel feed pipe open at one end and adapted to` be connected to a gas supply main at the other end, an air feed pipe having aninside diameter greater than the outside diameter of the fuel feed pipe, said air feed pipe surrounding the fuel feed pipe to provide an air passage around the outside of the fuel feed pipe and being open at one end adjacent the open end of the fuel feed pipe, the open end of the air feed pipebeing restricted a predetermined amount, said air feed pipe having longitudinally spaced groups of circumferentially spaced openings intermediate the ends thereof, a cover having an outwardly projecting wall secured ,to the air feed pipe adjacent each of said groups of openings, said covers having openings therein angularly disposed to effect circumferential and axial movement of air diseha ed therethrough, a housing covering the open en Ys of the fuel and air feed pipes and the said covers, and exhaust means communicating with the housing.

3. Combustion apparatus'comprising, in combination, a fuel feed pipe having a fuel outlet opening and adapted to be connected to a gas supply main at one end, an air feed pipe having an inside diameter greater than the outside diameter of the fuel feed pipe, said air feed pipe surrounding a portion of the fuel feed pipe to provide an air passage around the outside of the fuel feed pipe, said air feed pipe having longitudinally spaced groups of circumferentially spaced openings therein, a cover secured to the air feed pipe adjacent each of said groups of openings, said covers having jet openings therein angularly disposed to eect circumferential and axial movementof air discharged therethrough, a'housing covering the openings in the fuel and air feed pipes and the said covers, an exhaust pipe communicating with the housing, and means within the housing for increasing the heat transfer from the exhaust gases to the air injected through the air feed pipe.

4. Combustion apparatus comprising, in combination, an air feed pipe open at one end and having longitudinally spaced openings intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an openend near the open end of the air fed pipe, cover means adjacent the longitudinally spaced openings and having Jet openings for effecting rotary movement of air discharged therethrough, a housing spaced from and covering the open ends'of the fuel and air feed pipes andthe longitudinally spaced cover means, and an exhaust pipe communicating with the housing.

5. Combustion apparatus comprising, in combination, an air feed pipe having longitudinally spaced openings therein, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having a fuel outlet opening therein, cover means adjacent the longitudinally spaced openings and having jet openings therein for effecting rotary movement of air discharged therethrough, a housing spaced from and covering the openings in the cover means and fuel feed pipe," and an exhaust pipe communicating with the housing.

6. Combustion apparatus comprising, in combination, an air feed pipe open at one end and having longitudinally spaced openings intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced 'relation thereto and having an open end near the open end of the air feed pipe, vanes secured to the fuel feed pipe adjacent the longitudinally spaced openings for restricting the openings upon rotation of the fuel feed pipe, means adjacent the longitudinally spaced openings for eecting rotary movement of air discharged from the openings, a housing spaced from and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, and an exhaust pipe communicating with the housing.

A '7. Combustion apparatus comprising, in combination, an air feed pipe open at one end and having longitudinally spaced openings intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an open end near the open end of the air. feed pipe, vanes secured to the fuel feed pipe adjacent the longitudinally spaced openings for restricting the openings upon rotation of the fuel feed pipe, said vanes being circumferentially staggered so as to restrict the longitudinally spaced openings by different amounts, means for effecting rotary movement of air discharged from the' openings, a housing spaced from and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings. and an exhaust pipe communieating with the housing.

8. Combustion apparatus comprising, in combination, an air feed pipe ope'n at one end and having longitudinally spaced openings intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an open end near the open end of the air feed pipe, variable means for restricting the longitudinally spaced openings, means adjacent the longitudinally spaced openings for effecting rotary movement of air discharged from the openings, a housing spaced through and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, and an exhaust pipe communicating with the housing.

9. Combustion apparatus comprising, in combination, an air feed pipe having longitudinally spaced openings therein, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having a fuel outlet opening, variable means for restricting the longitudinally spaced openings, a housing spaced from and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, and an exhaust pipe communicating with the housing.

10. Combustion apparatus comprising, in com'- bination, an air feed pipe open at one end and having longitudinally spaced openings intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an open end near the open end of the air feed pipe, means adjacent the longitudinally spaced openings for effecting rotary movement of air discharged from the openings, a housing spaced through and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, the sizes of the fuel and air feed pipes and-the openings therein being so proportioned that between 30% and 50% of the air required for complete combustion of the fuel is discharged into the housing at the open end of the air feed pipe, and an exhaust pipe coinmunicating with the housing.

11. Combustion apparatus comprising, in combination, an air feed pipe open at one end and having longitudinally spaced openings of different sizes intermediate the ends, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an open'end near the open end of the air feed pipe, means adjacent the longitudinally spaced openings for effecting rotary movement of air discharged through the openings, a housing spaced from and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, and an exhaust pipe communicating with the housing.

12. Combustion apparatus comprising, in combination,` an air feed pipe open at one end and having longitudinally spaced openings of different sizes intermediate the ends, said openings increasing in size with the distance from the said open end, a fuel feed pipe extending through the air feed pipe in spaced relation thereto and having an open end near the open end of the air feed pipe, a housing spaced from and covering the open ends of the fuel and air feed pipes and the longitudinally spaced openings, and an exhaust means communicating with the housing.

13. Combustion apparatus comprising, in combination, an elongated housing having a closed end and an open end, substantially parallel fuel and air feed'pipes extending into the open end of the housing and having adjacent open ends spaced from the closed end of the housing to provide a combustion space at the closed end of the housing, said fuel and air feed pipes also being spaced from the housing to provide space for combustion therearound, said air feed pipe having longitudinally spaced openings within the housing and intermediate the ends thereof, the open end of the air feed pipe being so restricted and proportioned with respect to the longitudinally spaced openings that combustion is distributed Within the housing, means for variably restricting the longitudinally spaced openings, and exhaust means communicating With the open end of the housing.

14. Combustion apparatus comprising, in combination, an elongated housing having a closed end andan open end, substantially parallel fuel and air feed pipes extending into the open end of the housing and spaced therefrom to provide a combustion space within the housing, said fuel feed pipe having a fuel outlet opening therein, said air feed pipe having longitudinally spaced openings within the housing and intermediate the ends thereof, the openings in the air feed pipe being so restricted aid proportioned in size that combustion is distributed within the housing, means for variably restricting the longitudinally spaced openings, and exhaust means communicating with the open end of the housing.

15. Combustion apparatus comprising, in combination, an air feed pipe having a discharge end longitudinally spaced openings intermediate the ends thereof which openings progressively increase in size with their distance from the discharge end of the pipe, a fuel feed pipe spaced from and substantially parallel to the air feed pipe, a housing spaced from and covering portions of the air and fuel feed pipes and the longitudinally spaced openings, said housing having an exhaust opening therein.

yHENRY A. DREFFEIN.

, CERTIFICATE 011" CORRECTION.- Patent No.2,255,5}+0.' September 9, 19h11..

HENRY A. DREFFEIN.

- It is hereby certifie-d that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first vcolumn, line 22, for l"have" read -having; and. second co'lumn, line 5b.,

claim it, forffe'd pipe" read --feed pipe; page )4., first column, lines )i5 and 65, claims 8 and lO respectively, 'flor the wordlfrom" read --through- .Y

lines Miami 66, same claims, for ",throughl' vread. --from; end that the said Letters Patent .should be read with this correction therein that the same may conform to the record of the Case in the Patent Office.

signed and sealed this 23th day of octoer, A. D. 19M.

Henry Van Arsdale, .(Seal) Acting Commissioner of Patents. 

